Administrative Information

Repository Information

Conditions Governing Access note

The collection is open for research.

Conditions Governing Use note

Collection items available for reproduction, but the Archives Center makes no guarantees
concerning intellectual property rights. Archives Center cost-recovery and use fees
may apply when requesting reproductions.

Accruals note

An additional .15 cubic feet of material documenting the Holter Monitor was added
to the collection in February 2012.

Immediate Source of Acquisition note

The collection was donated by Del Mar Avionics through Bruce Del Mar, President on
September 12, 2011.

Collection documents the development of the Holter Monitor, a portable device for
continuously monitoring heart activity for an extended period, through engineering
logbooks, drawings, operator manuals, correspondence, photographs, sales brochures
and catalogs, biographical information about the engineering staff who worked on the
monitor, patents and trademarks, and marketing and sales materials.

Biographical/Historical note

Norman Jefferis “Jeff” Holter (1914-1983) was born in Helena, Montana, to a prominent
Montana pioneering family. After attending public schools in Helena, he earned master’s
degrees in chemistry from the University of Southern California (1938) and physics
from the University of California, Los Angeles (1940). During these years Holter also
organized Applied Micro Sciences, a scientific photography business, and began working
with Dr. Joseph A. Gengerelli of UCLA on nerve stimulation in frogs and brain stimulation
in rats. Holter's interest in studying electrical activity in humans in their daily
activities without touching them, spawned his lifelong pursuit to develop the Holter
Monitor.

During World War Two, Holter served as a senior physicist for the U.S. Navy's Bureau
of Ships, conducting research into the behavior of ocean waves in preparation for
wartime amphibious operations. After the war, in 1946, Holter headed a staff of oceanographic
engineers at Bikini Atoll during Operation Crossroads, the first postwar atomic bomb
tests, measuring wave actions and underwater disturbances caused by the explosions.

Because of demands of his family's business affairs, Holter returned to Helena in
1947 to continue his research activities. In 1947 he formed the Holter Research Foundation,
with a laboratory originally located in the rear of the Holter Hardware Company building.
From 1956 to 1971 the laboratory facilities were located in the Great Northern Railroad
depot building in Helena. The foundation was initially funded by Holter and other
members of his family, but in 1952 Holter began to receive grants from the National
Institutes of Health (NIH).

Holter continued his collaboration with Dr. Gengerelli of UCLA in attempting to transmit
information, primarily brain waves, by radio. Holter turned his attention from the
brain to the heart because the heart's greater voltage made the electronics easier,
and because heart disease was far more prevalent than cerebral disease. Holter’s introduction
to Dr. Paul Dudley White (1886-1973), a renowned physician and cardiologist, helped
convince him to focus his research on recording electrical activity from the heart.
Holter's goal was to radio broadcast and record the more obvious electrophysiological
phenomena occurring in humans while carrying on their normal activities, rather than
having to lie quietly on a couch.

The first broadcast of a radioelectrocardiogram (RECG) took place circa 1947 and required
eighty to eighty-five pounds of equipment, which Holter worn on his back while riding
a stationary bicycle. This was not practical and in no way could be worn by a patient.
The initial transmitter and receiver required that the subject remain in the general
area of the laboratory, so a portable and lighter RECG receiver-recorder had to be
developed.

Next, Holter created a briefcase-like device that could be carried by a patient. By
using very thin magnetic recording tape, twenty-four hours of RECG could be captured
on a reel five inches in diameter. The initial method of examining the voluminous
records from the tape recordings developed by Holter was called Audio-Visual Superimposed
ECG Presentation (AVSEP). AVSEP made it possible to examine twenty-four hours of RECGs
in twenty minutes, with signals being presented visually on an oscilloscope and audibly
through a speaker.

With the development of transistors, radioelectrocardiography was made obsolete, and
it became possible for the amplifier, tape recorder, temperature-control circuits,
motor speed control circuits, and batteries to be placed in a single unit small enough
for a coat pocket or purse. In 1952, Holter succeeded in creating a small unit that
weighed 1 kilogram. Wilford R. Glassock, a senior engineer working with Holter, traveled
to Cedars of Lebanon Hospital (now Cedars-Sinai Hospital of Los Angeles) in 1962 to
demonstrate the Holter monitor system and discuss making it more practical. At Cedars,
Dr. Eliot Corday observed the practicality of the system and not only embraced the
technology, but collaborated with Holter’s team and was an early promoter of the technology
to both industry and physicians. Holter and Glassock were issued US Patent 3,215,136
on November 2, 1965 for the Electrocardiographic Means.

As articles describing the foundation's invention of these devices began to appear
in the professional literature, there was considerable demand from doctors and hospitals
for the equipment. Dr. Corday introduced Holter to Bruce Del Mar, founder of the Del
Mar Avionics Corporation in Irvine, California. Del Mar engineers developed the “electrocardiocorder”
for clinical use, producing a commercially viable monitor which came to be known as
the Holter Monitor Test. Further refinements led to the creation of a "minimonitor"
in 1968, which was described by Holter as being the "size of a cigarette package."
Commercial production of the Holter minimonitor, AVSEP, Jr., began in 1969. The Holter
Research Foundation ultimately sold exclusive rights to their patents to Del Mar Engineering
Laboratories.

Later known as Del Mar Avionics, a team of engineers diverted their attention from
successful manufacturing of military weapons training devices to focus on improving
the speed and accuracy of computerized ECG analysis and they became the acknowledged
leader in Holter monitoring technology for over 40 years. In 1969, because of the
increased amount of required paper work and red tape, Holter canceled the grant funding
his foundation had been receiving from NIH. He was also in constant conflict with
the Internal Revenue Service over the foundation's non-profit status, rights to patents,
and commercial production of equipment. The foundation continued to maintain a laboratory
and conduct varied scientific work, but on a much smaller scale. The Holter Research
Foundation, Inc. was dissolved in 1985, two years after Holter’s death.

Del Mar Avionics was founded on January 9, 1952, as Del Mar Engineering Laboratories
in Los Angeles, California by Bruce Del Mar, who led the development of aircraft cabin
pressurization systems. Del Mar was born in Pasadena, California in 1913. An engineer,
inventor, entrepreneur and businessman, Del Mar graduated from the University of California,
Berkeley (1937) with a Bachelor of Science degree. Del Mar worked for Douglas Aircraft
(1933-1951) as a research engineer on many projects before founding Del Mar Engineering
Laboratories. In 1938, Del Mar married Mary Van Ness. The couple had two daughters,
Patrica Jean Parsons and Marna Belle Schnabel.

In 1958, Del Mar formed a wholly-owned subsidiary, Electromation Inc., which manufactured
tape recording and communication equipment. He later established, Aeroplastics Corporation
to manufacture plastic products and Avionics Research Products Corporation to develop
and produce biomedical instrumentation. By the mid-1960s, the company had become a
leading U.S. Defense Department prime contractor in the development and production
of aerial tow target systems for weapons training and instrumented ground targets
for scoring air-to-ground automatic weapons delivery. It also produced helicopter
target drones and helicopter flight trainers for the U.S. Army.

In 1961, the company entered the growing medical instrumentation market with the development
of the first long-term ambulatory monitoring systems.

In 1965, the company introduced the Hydra Set Load Positioner that controls the precise
vertical positioning of loads up to 300 tons (272,000 kg) in increments as small as
0.001 inch (0.025mm). This unique product, mounted between the load and the crane
(or hoist), permits precise mating and de-mating of critical components, thus eliminating
unforeseen damage to valuable loads. Hydra Set Load Positioners are in use worldwide
in the aerospace, military/commercial aviation, nuclear and fossil fuel power generating
industries and in various industrial applications. In 1975, the company, then re-named
Del Mar Avionics, moved to its current location in Irvine, California.

Scope and Contents note

The collection includes engineering logbooks, drawings, operator manuals, correspondence,
photographs, sales brochures and catalogs, biographical information about the engineering
staff who worked on the monitor, patents and trademarks, and marketing and sales materials
documenting the development of the Holter Monitor, a portable device for continuously
monitoring heart activity.

The records document the successful collaboration of an independent inventor and a
manufacturing firm to identify problems, develop solutions and bring to market diagnostic
technologies. Bruce Del Mar’s role as an innovator and collaborator with Holter is
especially important, because Del Mar's work spurred the development of an entire
diagnostic industry. In addition, the records also chronicle how “Holter technology”
was affected by progressive technological innovations in the industry, as vacuum tubes
were replaced by transistors, as microprocessors gave way to microchips and circuit
boards, and as analog recordings were replaced by digital formats.

Documenting manufacturing developments (highs and lows) and marketing considerations
is an important element in better understanding the invention process. Del Mar Avionics
was the first to design and manufacture instrumentation for long-term monitoring of
the human heart for the medical profession. Today, Holter Monitors continue to be
an important diagnostic tool for monitoring the health of the heart.

Series 1, Historical Background, 1951-2010 and undated, consists of biographical materials for Bruce Del Mar, founder of Del Mar Avionics,
company histories, copies of the Del Mar Avionics newsletter
Pacemaker, employee information, newspaper clippings and ephemera, and photographs of some
employees. The employee information contains a 1979 handbook, explaining company policies
and the benefits of employment with Del Mar Avionics and a 1951 memo detailing overtime
working hours for women, presumably from Douglas Aircraft, where Bruce Del Mar was
employed.

Series 2, Del Mar Avionics Engineering, 1958-1976, is divided into three subseries, Subseries 1, Correspondence, 1965-1976; Subseries
2, Reports, 1964-1969; and Subseries 3, Drawings, 1958-1968. The documentation consists
primarily of correspondence from the engineering department, 1965 to 1976, related
to the development, design, budgeting, testing, and marketing of the Holter Monitor.
The majority of the documentation is correspondence and is written by engineering
staff members, but also included are quotation requests, trip reports, and technical
reports. Correspondence between Holter and Del Mar about the development of the Holter
Minotor is in Series 6. The drawings, 1958-1968, include six drawings (22" x 34" or
smaller) for Avionics Research Products projects (panel assembly, chassis assembly,
and battery chargers for model 602), and Electromation Company (degausser single coil).

Series 3, Patents and Trademarks, 1965-2002 and undated, consists of copies of patents by Norman J. Holter, W.E. Mills, and W.E. Thornton,
Cliff Sanctuary. and Isaac Raymond Cherry related to the development of the Holter
Monitor. Also included are lists of United States patents issued to Del Mar Avionics
employees, as well as lists of registered trademarks and activities for Del Mar Avionics
and copies of trademarks issued to the company.

Series 4, Product Literature, 1968-2010 and undated, consists of product literature for Del Mar Avionics products and some of its competitors.
The product literature for Del Mar Avionics is arranged chronologically by model number,
and the competitor literature is arranged alphabetically. All of the product literature
is related to medical instrumentation with the exception of the Hydra Set, a precision
load positioner which is the only product Del Mar Avionics sells today.

Holter and Wilford R. Glassock were issued United States Patent 3,215,136 on November
2, 1965 for the Electrocardiographic Means. Dr. Eliot Corday introduced Holter to
Bruce Del Mar, founder of the Del Mar Avionics Corporation in Irvine, California.
Del Mar engineers developed the “electrocardiocorder” for clinical use, producing
a commercially viable monitor which came to be known as the Holter Monitor Test. Further
refinements led to the creation of a "minimonitor" in 1968 which was described by
Holter as being the "size of a cigarette package." Commercial production of the Holter
minimonitor, AVSEP, Jr., began in 1969. The Holter Research Foundation ultimately
sold exclusive rights to their patents to Del Mar Engineering Laboratories.

The materials include biographical materials about Norman J. Holter, journal articles
about the Holter Monitor, correspondence, engineering notebooks, a licensing agreement,
product literature, reports, price lists, catalogs, operating manuals and specific
information about the Dynamic Del Mar Avionics ElectroCardioCorder (Model 445), 1977,
and the ElectroCardioScanner (Model 660), 1971. Both models were developed by Del
Mar’s medical device manufacturing staff. The licensing agreement and correspondence
detail in chronological order the relationship between Norman Holter and Del Mar Avionics,
specifically president Bruce Del Mar, in the rapid commercial marketing and development
of Holter's electrocardiorecorder. Although Holter assigned exclusive rights to his
patent to Del Mar Avionics, he was involved in the design and development process,
albeit from a distance. The engineering staff at Del Mar kept Holter informed, and
it is clear that Holter regularly visited the company.

The engineering notebooks relate to the models 445 and 660. The notebooks were maintained
by engineering staff members D. Anderson, N. Mohammedi, Ray Cherry and Fike. The notebooks
are handwritten, although in some instances memos and other information have been
inserted. For example, N. Mohammedi's notebook documenting Model 445 contains black-and-white
prints, magnetic tape samples, and recorder tape (EKG graph paper) samples with data
from the monitor. The notebooks are bound and paginated, and individual pages are
stamped sequentially.

Series 7, Slides, circa 1990s, consists of color slides used for presentations by Del Mar Avionics staff to discuss
and promote the marketing of the Holter Monitor.

The James A. E. Halkett and Sigmund A. Wesolowski, M.D., Papers, 1948-1951 (AC0200)
documents Halkett and Wesolowski’s experiments on an early mechanical heart. Halkett
and Wesolow(ski) materials show the process of technological innovation through laboratory
protocols.

The George Edward Burch Papers, 1984-1986 (AC0316) documents Burch’s pioneering work
in clinical cardiology and research through technical notes, diagrams, and correspondence
regarding laboratory work on the "2-pump heart model,” 1984-1986.

The Ronald J. Leonard Papers, circa 1980-1997 (AC1109) documents Leonard's development
of pumps and oxygenators used in cardio-pulmonary bypass surgery.

Materials in the Division of Medicine and Science, National Museum of American History

The Division of Medicine and Science holds two monitors: the Dynamic and the Del Mar
Avionics ElectroCardioCorder (Model 445), 1977 and the ElectroCardioScanner (Model
660), 1971. Both were developed by Del Mar’s Medical Device Manufacturing staff. See
accession #: 2011.0196.

Materials at the Montana Historical Society Research Center, Archives

Holter Family papers, 1861-1968

Includes documentation about the Holter Research Foundation, Inc.

Holter Research Foundation, Inc. records, 1914-1985

The Holter Research Foundation, Inc. was a private, non-profit, scientific research
foundation started in Helena, Montana, in 1947 by Norman J. "Jeff" Holter. Records
(1914-1985) include correspondence, financial records, laboratory records, subject
files, photographs, etc. Also included are subgroups for N.J. Holter; his work in
the U.S. Navy on bombs and waves; his work as assistant chancellor at University of
California, San Diego; and the Society of Nuclear Medicine.